parasite image database

Bursate

Ancylostomatoidea - Hookworms

Ancylostoma braziliense

Buccal cavity of adult A. braziliense. Note the single pair of cutting teeth

​Ancylostoma caninum

Egg of A. caninum. Eggs have an elliptical shape, thin shell, and are approximately 52-79 X 28-28 µm. In fresh feces eggs contain morula, which develop to first stage larvae within eggs in the environment.

​Ancylostoma caninum

Buccal cavity of adult A. caninum. Note the three pairs of cutting teeth. Pathogenesis of infection with A. caninum is associated with feeding habits of the adult parasite, which leads to bloodloss of an estimated .01-.09ml/worm/day.

​​Ancylostoma caninum

Male and female Ancylostoma caninum recovered from a dog. Adults males are usually 10-12 mm in length, and the females average 14-16mm in length. Prepatent period varies by route of transmission and can be as short as 2 weeks when larvae are ingested or as long as 4 weeks when larvae are acquired by dermal penetration.

​Ancylostoma caninum​​In situ photo of Ancylostoma caninum found on necropsy of a dog. Infected dogs may present with anemia from blood loss due to worm feeding, skin lesions associated with penetration of third-stage larvae, diarrhea associated with fourth-stage larvae damaging the small intestine, and/or hemorrhagic pneumonitis associated with larval migration.

​Ancylostoma caninum

Adult of A. caninum in small intestine from dog at necropsy. Note the area of hemorrhage surrounding the adult.

​Ancylostoma tubaeforme

The bucal cavity of the hookworm of cats. Although very similar to the stoma of adult Ancylostoma caninum, the teeth on the ventral margin of A. tubaeforme are slightly larger. Infection with this species is the result of skin penetration or ingestion of third-stage larvae, or ingestion of paratenic hosts with larvae encysted in tissues.

​Bunostomum spp.

Species of Bunostomum most commonly infect ruminants. A large buccal cavity with cutting plates helps differentiate these hookworms from other intestinal parasites.

​Bunostomum phlebotomum

A parasite of cattle and zebu, Bunostomum phlebotomum may be found in the small intestine feeding on blood. Penetration of larvae may cause cattle to stamp their feed and lick their legs, and heavy infections with adults may lead to diarrhea, anemia, and hypoproteinemia. In calves this manifests as marked weakness, emaciation, and submandibular edema.

​​Uncinaria stenocephala

Egg of Uncinaria stenocephala. This hookworm infects dogs (rarely cats) in cooler temperate regions, including the northern US, Canada, and Europe. Eggs resemble those of Ancylostoma spp. in that they are elliptical, thin-shelled, and contain morula in fresh feces, but Uncinaria eggs are slightly larger (71-92 X 35-58µm).

​​Uncinaria stenocephalaandAncylostoma caninum

Eggs of U. stenocephala and A. caninum together in a 10X field of view. Note the size difference between eggs of the two species. Photomicrograph provided by Dr. Michael Dryden, Kansas State University.

​Uncinaria stenocephalaand Ancylostoma caninum

Egg of A. caninum on the left and U. stenocephala on the right in 40X field of veiw. Photomicrograph provided by Dr. Michael Dryden, Kansas State University.

​Uncinaria stenocephala

Buccal cavity of Uncinaria stenocephala. Note the two cutting plates.

Dioctophymoidea

Dioctophyme renale

Eggs of the giant kidney worm, Dioctophyme renale, are passed in the urine of infected hosts. Eggs have a thick, rough shell and measure 60–80µm by 39–46 µm.

​Dioctophyme renale

Adult Dioctophyme renale in the kidney of a dog. Primarily a parasite of mink, other animals including dogs and other canids, otters, and occasionally pigs, horses, cattle and humans may be infected. ​

​Dioctophyme renale

Adult Dioctophyme renale removed from a coyote. Adult females may reach 103 cm in length, making D. renale the largest nematode known to parasitize humans.

Metastrongyloidea

Aelurostrongylus abstrusus

First-stage larva of A. abstrusus can be recovered from the feces of infected cats using a Baermann apparatus or zinc sulfate flotation. Larvae are approximately 300–400µm by 15–20 µm with a terminal S-shaped kink and dorsal spine.

​Crenosoma vulpis

Anterior end of Crenosoma vulpis showing the overlapping circular folds unique to the family Crenosomatidae. Adults of this genus are found in the bronchi and trachea of animals. Cresonema vulpis is a cause of substantial chronic tracheobronchitis in captive fox.

Goat lungs showing classic Muellerius capillaris lesions. Adult worms of this genera live in the alveoli and pulmonary parenchyma of sheep and goats. There, they form nodules that turn a greyish color, a result of the degeneration of accumulated leucocytes and necrotic pulmonary tissue. Despite this, hosts generally show no apparent clinical signs.

​Parelaphostrongylus tenuis

First-stage larva of P. tenuis from a white-tailed deer. Larvae are readily recovered using a Baermann apparatus and measure 310–380 µm in length. Larvae have an S-shaped kink in the tail and a dorsal spine.

​Parelaphostrongylus tenuis

Adult Parelaphostrongylus tenuis adults in the subdural space of a white-tailed deer. Adults are 39-91 mm in length.

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​Parelaphostrongylus tenuis

Neurologic goat infected with Parelaphostrongylus tenuis. When P. tenuis infects a host other than the white-tailed deer, the larvae migrate aberrantly, usually causing damage to the dorsal horns of the grey matter of the spinal cord. Small ruminants are particularly susceptible to neurologic disease due to aberrant migration of P. tenuis.

​Protostrongylus rufescens

Nodules of P.rufescens in sheep lung. Adult P. rufescens live the small bronchioles and may induce nodule formation.

Stephanurus dentatus

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Adult Stephanurus dentatus removed from the kidney of a pig. Known as the kidney worm of swine, adults are found in the perirenal fat, the renal pelvis, and the walls of the ureters. Adult males are 20-30 mm and females are 30-45 mm in length.

Adult Stephanurus dentatusexcised from cysts in the perirenal fat surrounding the ureter of a pig. Adults are usually found in cysts that communicate with the ureter through which they pass their eggs. The eggs leave the host via urine. Host infections may be acquired through ingestion of third-stage larvae, ingestion of a paratenic host, or from dermal penetration by the third-stage larvae. The larvae then migrate extensively through the organs.

Strongyloidea - Large and Small Strongyles

Strongyle-type egg

Eggs of Strongyloidea have this typical morphology. They are elliptical, have a thin shell, and are approximately 65-100 X 34-50 µm, depending on the species. In fresh feces eggs contain morula which develop into first stage larvae within eggs in the environment.

​Strongyle-type egg

A larvated strongyle egg is shown. Larvated eggs are often seen in fecal samples that have been stored for several days before processing.

​Small strongyles

Various preserved species of adult small strongyles.

​​Small strongyle

​Buccal cavity of a small strongyle adult. Buccal cavities of small strongyles are smaller than those of large strongyles. Also, note the outer leaf crown on this specimen.

​Strongylus spp.

Preserved large strongyles (Strongylus spp.) adults.

​﻿​Strongylus edentatus

Strongylusedentatus is differentiated from other members of the genus by a buccal capsule that it is wider anteriorly than at the middle and, as suggested by the species name, a lack of teeth.

​​Strongylus equinus

The buccal capsule of Strongylusequinus. Strongylus equinus makes an extensive migration through the abdominal cavity, taking 260 days to molt and mature to a patent adult.

Colic in horses may result from migration of juvenile S. vulgaris through the cranial mesenteric artery.

​​Gross lesion due to horse strongyles

Thrombosis in the illiac artery of a horse, a result of migrating juvenile strongyles.

Trichonematidae

Chabertia ovina

Buccal cavity of an adult Chabertia ovina. The large buccal cavity of this parasite is used to hold a plug of mucosa in the colon of sheep, goats, and cattle throughout the world. This parasite actually feeds on the granular layer that it digests with its esophageal secretions. Blood feeding is incidental and may be a cause for frank blood in the feces of the host.

Oesophagostomum radiatum

The anterior portion of the nodular worm of cattle, zebu, and water buffalo. It is known as the nodular worm for the characteristic nodules it forms in the colon of its host. Oesophagostomum radiatum is one of the more pathogenic species of helminths of cattle when found in large numbers.

​Oesophagostomum columbianum

​Nodlues formed by Oesophagostomum columbianum in the colon of a sheep. Oesophagostomum columbianum is a parasite of the colon of sheep, goats, camels, and wild antelope. Their larvae encyst anywhere from the pylorus to the colon to complete their development and become adults that attach in the colon. Frequently, the larvae nodules become abcesses that are filled with caseous material.

Trichostrongyloidea

Trichostrongyle-type egg

With the exception of Nematodirus spp., eggs of Trichostrongyloidea species have this typical morphology. They are elliptical, have a thin shell, and are approximately 65-100 X 35-50 µm, depending on the species. In fresh feces eggs contain morula which develop to first stage larvae within eggs in the environment.

​Cooperia spp.

Transverse striations along the cuticle of a Cooperia sp. adult cleared in lactophenol.

​Dictyocaulus spp.

Dictyocaulus viviparus first-stage larva recovered from bovine feces. These larvae are approximately 300-360 µm in length and are best recovered using a Baermann on fresh feces.

​Dictyocaulus viviparus

Adult Dictyocaulus viviparus seen in the bronchi of a steer. Dictyocaulus viviparus parasitizes cattle, deer, reindeer, buffalo, and camels. Adults may reach 4-8 cm in length.

​Haemonchus spp.

Species of Haemonchus are referred to as barber-pole worms. Their common name reflects the distinct appearance of the female worms - a white uterus wrapped in a spiral fashion around the blood-filled intestines, which appear red in fresh worms.

​﻿Haemonchus contortus

Haemonchus contortus are shown feeding in the abomasum of a sheep. When the adults and fourth stage larvae move and leave their initial feeding sites, the wounds continue to bleed into the lumen of the abomasum.

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​Haemonchus contortus

Third-stage larvae of Haemonchus contortus suspended in a dew drop on grass. Hosts acquire infections with this parasite when they directly ingest larvae from pasture.

​Haemonchus contortus

Infection with Haemonchus may overwhelm a host's ability to replace proteins and blood lost. This results in decreased intravascular oncotic pressure resulting in edema. The gathering of edema in the submandibular area is termed 'bottle jaw'.

​Nematodirus spp.

Egg of Nematodirus sp. Eggs are elliptical, approximately 152-260 X 67-120 µm in size depending on the species, and contain two to eight distinctive large cells in fresh feces. ​

​Nematodirus sp.

Spicules and bursa of a male Nematodirus sp. Clinical signs of infection are associated with the emergence of larvae from the mucosa. This manifests as inappetence and acute enteritis.

​Ollulanus tricuspis

Larva of O. tricuspis. Third-stage larvae are approximately 500 um and have a tricuspid tail similar to that of the adult female (2nd and 4th stage larvae also have this type tail). Adults and larvae are found in the stomach of domestic cats and other felids. Diagnosis is based on the identification of larvae or small adults (1 mm) in vomitus using the Baermann test.

​Ollulanus tricuspis

A gravid Ollulanus tricuspis female. In this species, the larvae develop in the uterus of the female until they reach the third stage. Infection is spread when the larvae are vomited and another cat ingests them.

Ostertagia sp.

Portion of the anterior end of Ostertagia sp. showing the short buccal cavity and cervical papillae used to differentiate this worm from other trichostrongylids.

​Ostertagia ostertagi

Abomasum from a calf infected with O. ostertagia. The mucosal surface of the abomasum is covered with pin-head to pea-sized nodules as a result of invasion of juvenile worms into gastric glands.

​Trichostrongylus spp.

Adult Trichostrongylus species have a distinct excretory notch visible in the esophageal region.

​Trichostrongylus spp.

Species of Trichostrongylus are differentiated from other nematodes by the short and pointed spicules of males.